Autism-associated mutations in the Cavβ2 calcium-channel subunit increase Ba2+-currents and lead to differential modulation by the RGK-protein Gem

NEUROBIOLOGY OF DISEASE

卷:136

Article

Despang, Patrick¹  Salamon, Sarah¹  Breitenkamp, Alexandra F.¹  Kuzmenkina, Elza¹  Herzig, Stefan^1,2  Matthes, Jan¹ 

[1] Univ Cologne, Ctr Pharmacol, Gleueler Str 24, D-50931 Cologne, Germany

[2] Univ Appl Sci, TH Koln Technol Arts Sci, Cologne, Germany

关键词: Calcium channels;    Patch-clamp technique;    CACNB2 protein;    RGK protein;    Autism spectrum disorder;   

DOI  :  10.1016/j.nbd.2019.104721

来源: Elsevier

【 摘 要 】

Voltage-gated calcium-channels (VGCCs) are heteromers consisting of several subunits. Mutations in the genes coding for VGCC subunits have been reported to be associated with autism spectrum disorder (ASD). In a previous study, we identified electrophysiologically relevant missense mutations of Ca-v beta(2) subunits of VGCCs. From this, we derived the hypothesis that several Ca-v beta(2)-mutations associated with ASD show common features sensitizing LTCCs and/or enhancing currents. Using a Ca-v beta(2d) backbone, we performed extensive whole-cell and single-channel patch-clamp analyses of Ba2+ currents carried by Ca(v)1.2 pore subunits co-transfected with the previously described Ca-v beta(2) mutations (G167S, S197F) as well as a recently identified point mutation (V2D). Furthermore, the interaction of the mutated Ca-v beta(2) subunits with the RGK protein Gem was analyzed by coimmunoprecipitation assays and electrophysiological studies. Patch-clamp analyses revealed that all mutations increase Ba2+ currents, e.g. by decreasing inactivation or increasing fraction of active sweeps. All Ca-v beta(2) mutations interact with Gem, but differ in the extent and characteristics of modulation by this RGK protein (e.g. decrease of fraction of active sweeps: Ca-v beta(2d_G167S) > Ca-v beta(2d_v2D) > Ca-v beta(2d_S197F). In conclusion, patch-clamp recordings of ASD-associated Ca-v beta(2d) mutations revealed differential modulation of Ba2+ currents carried by Ca(v)1.2 suggesting kind of an electrophysiological fingerprint each. The increase in current finally observed with all Ca-v beta(2d) mutations analyzed might contribute to the complex pathophysiology of ASD and by this indicate a possible underlying molecular mechanism.